It is useful to be able to determine the mass of small particles or molecules. For example, by measuring the mass of a bio-molecule, one may be able to determine the type of the bio-molecule being tested. Mass sensors that are sensitive to small quantities of materials are useful in, for example, gas chromatography or mass spectrometry. There are many types of mass sensors that can determine the mass of small particles. For example, one type of mass sensor is the quartz crystal microbalance sensor, which uses a thin crystalline quartz disc placed between two electrodes. Another type of mass sensor is the microcantilever-based sensor that has several silicon nanowire-grown cantilevers. Yet another type of mass sensor is the surface acoustic wave sensor, which uses perturbations in surface acoustic waves to determine mass.